- The U.S. flu season is just beginning and can last through May.
- Peak infections generally hit the U.S. between December and February, according to the CDC.
- Predicting the duration and size of the outbreak isn't an exact science.
A surge in influenza cases in Australia and at least three deaths in the U.S. in recent weeks have some physicians worried that this year's flu season could be a bad one for Americans.
Though public health officials say they don't know yet whether the 2019-2020 season will be worse than usual, they are still urging people to get their flu vaccines before it kicks into high gear. Australia, which is just getting over its flu season, saw a surge in cases with the H3N2 strain.
Health agencies in Riverside County, California, Los Angeles County and Marion County, Indiana, have reported their first flu-related deaths of the 2019-2020 season. Nevada, Kentucky and Louisiana have also reported flu activity, Centers for Disease Control and Prevention spokesman Scott Pauley said.
"A death so early in the flu season suggests this year may be worse than usual," Dr. Cameron Kaiser, Riverside County public health officer, warned in a September news release announcing the fatality there.
The U.S. flu season is just beginning and can last through May. Peak infections generally hit between December and February, according to the CDC. It takes about two weeks for the vaccine to build an immunity to the disease.
Predicting the duration and size of the outbreak isn't an exact science.
"Flu season is never totally predictable," said Dr. Michael Ben-Aderet, associate director of Hospital Epidemiology at Los Angeles' Cedars-Sinai hospital. Changes in the flu virus, environment and even "some factors we honestly don't understand" can contribute to how the flu season hits nations, he added.
"It's still too early to tell what this flu season might be like," he said in an email. "The Australian season was bad, but the numbers were somewhat inflated by the fact that the season started earlier than normal and that caused a significant increase in testing."
The last severe U.S. flu season was the 2017-2018 season with an estimated 48.8 million people falling ill and 79,400 deaths, according to the CDC. Rough estimates from the CDC show that last year, there were 37.4 million to 42.9 million people who got the flu and 36,400 to 61,200 deaths.
"People can protect themselves by getting vaccinated," Ben-Aderet said. "Getting vaccinated is important not only for ourselves, but for the people around us."
This year's flu shot, the 2019-20 U.S. trivalent influenza vaccine, was updated based off the Southern Hemisphere's flu season and other increased flu activity.
For people who are concerned the influenza vaccine gives them the flu, Ben-Aderet said it's a "common misconception."
"There's no risk of getting the flu from the flu shot," he said, since the vaccine is composed of inactivated strains. Most people will just walk away with a sore arm. For people who do end up sniffling the next day, chances are they've caught one of the other respiratory viruses that pop up in the season.
Overall, Ben-Aderet stressed that people are much better off getting the flu shot than not.
The CDC recommends everyone over the age of 6 months to get vaccinated each year, with rare exceptions. There are different types of influenza vaccines, so what may work for a pregnant woman may not be the best bet for someone over 65. The CDC recommends talking over options with your doctor.